This application is a 371 of PCT/JP00/01136 filed Feb. 28, 2000.
The present invention relates to an angular velocity sensor employing a polycrystalline piezoelectric element.
In an angular velocity sensor known so far, a monocrystalline piezoelectric element is processed into a U-shaped tuning fork on which a driving electrode and a detecting electrode are attached. Such example is disclosed in Japanese Laid-open Patent No. 6-258333. A voltage is supplied to the driving electrode on this velocity sensor from a single driving power source, and an angular velocity signal is detected from the detecting electrode.
This angular velocity sensor requires a large electric power supply for enhancing a detecting sensitivity, and a large vibration amplitude must be generated. It is hence a problem that it is forced to use a nonlinear-operating-region, where the amount of dislocation due to vibration is unstable, of the piezoelectric element because of the large vibration amplitude, exceeding a linear-operating-region where the characteristic of the piezoelectric element is stable.
To solve the problem in the invention, a vibrator, which works as an inertia transducer by vibration and a Corioli""s force detector, is constructed comprising a piezoelectric element having a perovskite crystal structure expressed as ABO3, and the piezoelectric element includes 0.1 to 1.0 wt. % of MnO2. In this structure, a large vibration amplitude close to linear operation are obtained, and a high sensitivity is simultaneously achieved.